Well, your answer is definitely good but I can't seem to follow your method. It's a pain that we can't write these things out more clearly I think. It'd be good if we could use a font where they had Not A's and NotB's etc in them.

I think the way to proceed with that problem is to use the Race Hazard Theorem. I think I'll take a look at this later on in the afternoon and see what I can come up with.